This invention relates to a stitching apparatus for assembling uncured tire components such as plies on a tire building drum. Streams of air under pressure from nozzles positioned around the tire building drum stitch and eject air from under the tire components as the drum is rotated.
Stitching apparatus utilizing metal stitcher disks, such as those shown in U.S. Pat. No. 3,125,481 have been used to stitch tire tire components applied to a tire building drum. Improved apparatus to control the pressure applied by a stitcher disk is shown and described in U.S. Pat. No. 3,524,784. With these stitcher disks, the drum must be rotated a sufficient number of revolutions for the disks to traverse the distance between a position midway between the edges of the drum and the edges of the drum to press the tire components sufficiently to eject air and stitch the components together. Sufficient pressure must be applied to do the stitching, and at the same time, safeguards must be provided so that the green tire materials of the tire components are not distorted during this pressing action. Also, the moving parts on which the stitcher disks are mounted must be designed so that they can be adjusted for different size tires. Set up time is required which reduces time available for production time. The environment for the stitching rollers is not favorable and maintenance problems, such as failure of the roller bearings for the stitching rollers, are inherent with this type of stitching.
The present invention is directed to an improved stitching apparatus for stitching and ejecting air from layers of tire components applied to the cylindrical surface of a tire building drum. This is done with substantially no moving parts requiring a minimum of maintenance. Also, the stitching is done without contacting the tire components, resulting in substantially no distortion of the components during the stitching operation. The cycle time is reduced because the squeezing action is provided with a minimum of revolutions of the drum. Substantially no set up time for different size tires is required, hence the same set up can be used for stitching different width tire components.
In accordance with one aspect of the invention, there is provided a stitching apparatus for use with a tire building drum which is rotated for wrapping successive layers of tire components around a cylindrical surface of the drum comprising a supporting structure, a manifold mounted on the structure adjacent the drum in communication with a source of air pressure, characterized by nozzles in communication with the manifold positioned for directing streams of air through the nozzles under pressure against the layers of tire components on the surface, and means to rotate the tire building drum to expose successive portions of the layers to the streams of air as the tire components are carried past the nozzles on the rotating drum so as to stitch and eject air from the tire components.
In accordance with another aspect of the invention, there is provided a method of building a tire on a rotatable tire building drum comprising wrapping successive layers of tire component around the drum characterized by directing streams of air under pressure against the layers of tire components to press the layers together and eject air from between the layers as the drum is rotated.